Ozone (O₃): Causes & formation
Ozone (O₃) is a colorless to slightly blue and pungent to chlorine-like smelling gas. Under intense solar radiation, it is formed near the earth by the reaction of oxygen, nitrogen oxides and volatile organic compounds. At an altitude of 20 to 30 kilometers, it forms the protective ozone layer.
The precursor pollutants of the gas are mainly caused by humans, e.g. combustion plants, over-fertilized soils, solvents (including paints, varnishes, adhesives), combustion of fuel or electrical equipment such as printers.
Why do ozone levels rise in summer?
Ozone pollution increases in summer. On days that are sunny and windless, summer smog is particularly high. Meteorological conditions of summer high-pressure weather, such as high temperatures and strong solar radiation, thus promote the formation of the gas near the ground. In the afternoon hours, when the sun is at its most powerful, ozone levels are therefore also at their highest.
Ozone is not released directly. Rather, the intense solar radiation triggers complex photochemical processes in precursor pollutants. Nitrogen oxides and volatile organic compounds are formed. Therefore, ozone is considered more of a secondary pollutant.
To characterize ozone pollution, the O₃ value is measured over a period of eight hours, the mean value is calculated and given as a comparative value of 120 micrograms per cubic meter (µg/m³). Due to climate change, summer temperatures are rising, heat summers are becoming more frequent and thus the measured values are increasingly exceeding the recommended limit value. The alarm value (1h-mean value) of the Federal Environment Agency is 240 µg/m³.
How do you notice high ozone levels & what are the health consequences of the gas?
Ozone has a toxic effect on humans. Even in slightly elevated concentrations, it causes severe irritation of the mucous membranes and respiratory tract. In addition, the gas is oxidizing and can form ignitable and explosive mixtures. O₃ is absorbed through the breath and eyes and can cause lasting damage.
The symptoms of high ozone pollution are:
- Hoarseness
- Cough & Bronchitis
- Headache & Nausea
- Irritated, itchy and/or watery eyes
- Nosebleed
- Lack of concentration, drop in performance & fatigue.
At high O₃ concentrations, there is even a risk of pulmonary edema - water accumulation in the lungs.
What helps against too high ozone levels?
Protect yourself from summertime ozone pollution. With our tips, you can get through the summer smog more calmly:
- If possible, place sports and other physically strenuous activities in the evening or early morning hours. Avoid outdoor sports and physical exertion.
- Air your apartment best in the morning and evening. Keep the windows closed during the day when the sun is high.
- Drink significantly more than usual: ideally unsweetened beverages such as water and tea. On the other hand, avoid sugared and alcoholic beverages.
- Refrain from using products that emit ozone.
- Measure the O₃ content in your rooms and ventilate as needed, i.e. when the concentration exceeds the recommended limit value
It is best to test the indoor air with an air meter such as the air-Q.
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